Applicant's earlier-filed U.S. patent application Ser. No. 08/723,636, (sometimes referred to herebelow as the “parent application”) describes certain methods and apparatus for determining the presence of one or more analytes in a complex matrix (i.e., a matrix which includes many diverse physical and/or chemical species, some or all of which may interfere with the intended analysis). The types of complex matrices in which applicant's analytical methods and apparatus may be used include foods, biological fluids (e.g. blood cerebrospinal fluid), cosmetic preparations, pharmaceutical preparations, etc.
The methods and apparatus described in parent application Ser. No. 08/723,636 include a test apparatus which generally comprise a) a first sample-receiving chamber, b) a second filtrate-receiving chamber fluidly connected to the first sample receiving chamber, and c) one or more membranes positioned between the first and second chambers. Initially, a quantity of the flowable, analyte-containing matrix is dispensed into the first chamber. The sample is then caused to flow through the membrane(s) which remove selected matter (particles, large molecules, secondary analytes, etc.) from the matrix, and the resultant filtrate is allowed to pass into the second chamber. After the filtrate has entered the second chamber, reagent(s) is/are added to such filtrate to facilitate qualitative or quantitative determination (spectrophotometric, visual, etc.) of primary analyte contained within the filtrate. In instances where multiple membranes have been employed, one or more of those membranes may have been used for the purpose of capturing one or more secondary analyte(s) which were present within the matrix along with the primary analyte. In those instances, the analyte-capturing membranes may subsequently be removed, and the secondary analyte(s) may then be eluted (e.g, released, washed) from those capture membranes and into secondary receiving chamber(s). Appropriate reagents are then added to the eluant(s) contained within the secondary receiving chamber(s) to facilitate qualitative or quantitative determination (e.g., spectrophotometric, visual) of the secondary analyte(s).
Applicant has now devised a number of improvements, additions and modifications to the test methods and apparatus described in parent application Ser. No. 08/723,636, and such improvements, additions and modifications are described and claimed in this continuation-in-part application.